You almost feel sorry for the BMW M4 CSL. Those three letters at the end of the name are quite a burden to carry - a monkey on the car’s back it doesn’t really have any chance of shaking off. The last time they were used, I’m sure most of those reading this will know, was for the E46 M3 CSL, which enjoys near-god-like status for a lot of petrolheads.
The M4 CSL never had a hope of truly measuring up to this car. It can’t have a naturally aspirated inline-six that tops out at 8,000rpm. It wasn’t ever going to be possible to make it weigh as little as 1380kg, and with the pig-nosed 4 Series as a starting point, it had little chance of looking classically pretty.
Testing this car, then, involves trying to ignore the past and judging the new CSL in a modern context. And on that front, there’s plenty here to intrigue, kicking off with the weight reduction. Binning 100kg of bulk is an impressive feat, something BMW managed by swapping in carbon ceramic brakes, lighter wheels (which also help reduce unsprung mass), springs and struts, plus a bonnet made from carbon fibre-reinforced plastic.
That bonnet features two recessed sections finished in naked(ish) carbon and surrounded by red accents, which go with red pin-striping down the lower sides of the car and on the roof (also bare carbon), red backings for the badges, and a lipstick-like red surround for the giant kidney grilles. And if that wasn’t enough to take in, there are yellow daytime running lights, a reference to racing BMWs of the past - something also found on the M3 CS we tested not long ago. In the metal/carbon fibre-reinforced plastic, this all works together much better than you might expect.
Another version obvious change is inside the car - a missing rear seat bench, which sheds 21kg on its own. Left where that used to be are two large indentations intended to carry helmets, with a luggage net over the top.
There are also carbon fibre bucket seats in the front which drop the weight further. Something you can’t see, meanwhile, is a reduction in sound-proofing material. The result is…a car that’s still pretty hefty at over 1600kg, but it is lighter than the smaller M2. And in any case, that’s a decent figure these days.
To go with the lower weight figure, there’s more power, with an ECU tickle bringing the S58 twin-turbo inline-six’s output from 503bhp to 542bhp, knocking a couple of tenths off the 0-62mph time to provide a new figure of 3.7 seconds. Power goes to the rear via an eight-speed automatic gearbox, so that’s at least one thing the new CSL has over the old one with its ponderous robotised manual ‘SMG’ arrangement.
There are plenty of chassis changes to go with the reduced weight and increased power. The cast aluminium strut braces (one above and one below) are new, while the springs, dampers, anti-roll bars and camber angles have all been fiddled with to make the car sharper to drive. It sits 8mm lower than before, too.
The result is something that’s feisty, almost to the point of being a touch scary. It’s a car that feels on edge and one that needs to be respected. The uplift in power and pointier nature of the chassis make for a car much more mobile at the rear, which takes some getting used to.
The firmer setup and tweaked camber bring a lot more life to the steering and give the feeling of a front end that’s even more willing to change direction than that of a standard M4 Competition.
The tradeoff is ride comfort - this is a conspicuously firm car, although you can mitigate this by programming one of the two customisable modes (accessed via those very red tabs on the steering wheel) to have the suspension in its softest setting while turning everything else up, something we have to do an awful lot with performance cars these days. There’s call here not to use the sportiest steering setting, too - it’s too heavy.
It’s worth noting that the handling experience of the CSL can potentially be very different - it’s available with super-sticky (and quite fast-wearing, if you take them on track) Michelin Pilot Sport Cup 2R tyres, but our test car came on Pilot Sport 4 S rubber. Being more useful in a wider range of conditions, this is probably for the best, but we are left intrigued and how much extra potential could be unlocked from those chassis changes were the footwear different.
I am also left wishing BMW would have left the engine alone. More power through higher turbo boost pressure means noticeably more lag, and even less time you’re able to keep your foot down before having to back off. 503bhp was perfectly fine, BMW - this is overkill.
You do hear a lot more of that engine, although it's hard to tell how much of that is down to the reduced soundproofing, how much is due to the missing rear seat bench and what effect the new titanium exhaust has. You've probably noticed before how much boomier your car tends to be when folding your rear seats down, with the back of the car acting as a sort of echo chamber for the exhaust.
Whether or not the S58 twin-turbo six is something you want to hear a lot more of is debatable. It’s a much more ‘ordinary’ sounding lump than the old S55, making a noise that’s not dissimilar to the single-turbo B58 BMW that fits in just about everything. The binned soundproofing and rear seat also make for a car that’s noisier on long cruises, but not unacceptably so.
BMW has made a decent fist of making the eight-speed automatic gearbox feel aggressive on the upshifts, and it goes about its business in an efficient enough way, even if it can’t quite stop us from missing the old DCT.
It’s an odd car to unpack, the M4 CSL. It seems a little silly to have such a big car that’s only a two-seater, but that does make us admire both the commitment of BMW and anyone who’s bought one. And on that front, it didn’t need to convince many to get on board with such an idea, nor enough people to be happy to part with £128,820, because only 100 came to the UK out of a total 1,000 units built.
Yes, £128,820, for a car that’s definitely sharper to drive, but is it £50k better than an M4 Competition? Perhaps not, and in this quest to make a more focused version of the M4, BMW has brought out something that just doesn’t feel as cohesive as a Comp.
Then again, a quick peruse of the classifieds reveals that - at the time of writing - there’s an approved used version with a mere 216 miles on the clock going for £99,850, and others for not much more. For that kind of money, the CSL suddenly looks a lot more interesting.